It is well-known that infusion is effected by subjecting the substance to be infused, for example coffee, to the action of a hot liquid (generally water, sometimes milk) to extract the soluble constituents of the substance, the mixture of water/soluble constituents being collected in a receptacle.
For coffee it is common practice to pour on the hot water in one pass. However, for several reasons this is not an optimum method, i.e. particularly at the beginning the coffee particles are not wetted, swollen and heated adequately and the water passes through too rapidly without proper infusion of the coffee. To improve the efficiency and the quality of extraction of soluble constituents it has been proposed to pour on the hot water in a plurality of steps. This is described in the document DE-A-39 09 626. For this the water to be infused is divided into a pre-wetting quantity, poured on in a first step, and additional quantities, poured on subsequently. Pre-wetting is followed by a waiting time in which the coffee is allowed to swell under the influence of the poured-on hot water. After this, the rest of the water is poured on in one or more further steps.
For this, said document proposes to effect these operations by defining time intervals in which infusion of the coffee with hot water is either allowed or inhibited. This is achieved by influencing the time of heating of the water contained in the reservoir. However, the user will not always use the same quantities of water, which may give rise to some practical problems, for which said document does not provide a solution. In particular, the optimum pre-wetting quantity of water for a small number of cups may differ substantially from that for a large number of cups. No means are revealed to adapt the pre-wetting quantity of water to the quantity of coffee or to the quantity of water put into the coffee-maker.